Originally Posted by Amazing KG3
high grade BBs are refined to a perfect sub milimeter finish, and are polished, crossmans arent and could damage the barrel, youll also find that with a light .12, your rounds will go anyways but straight.
One of our guys put some through a stock TM M4 (no idea why...) Even with the slightest hopup setting, they curved up at nearly a 45 degree angle about 15 ft after leaving the barrel.
So not only will they possible destroy your gun, they aren't combat effective at all. Maybe save them for a springer or for filling an airsoft claymore perhaps.